P1096: TREATMENT PATTERNS AND OUTCOMES IN RELAPSED/REFRACTORY MANTLE CELL LYMPHOMA
Authors: A. Bock, K. Poonsombudlert, M. Larson, J. Gile, R. Tawfiq, S. Maliske, M. Maurer, J. Cerhan, X. Andrade-gonzalez, A. Saliba, J. Paludo, D. Inwards, S. Ansell, T. Witzig, T. Habermann, B. Link, S. Ayyappan, G. Nowakowski, U. Farooq, Y. Wang
Journal: HemaSphere (2022)

Background: Mantle cell lymphoma (MCL) is an incurable B-cell lymphoma with heterogeneous clinical presentation and no established standard of care. In the last two decades, the pattern of frontline therapy for MCL has evolved, and multiple new agents became available for relapsed/refractory (R/R) MCL. The pattern of treatment, its evolution with time, and the association with treatment outcomes in R/R MCL are not well understood. Aims: To characterize second line (2L) treatment patterns and outcomes in patients with R/R MCL initially diagnosed in the rituximab era. Methods: Patients with newly diagnosed MCL between August 2002 and April 2015 and followed through 2021 were identified from the Mayo Clinic/University of Iowa Molecular Epidemiology Resource (MER) prospective cohort study. Patients who initiated therapy for R/R MCL after relapse or progression to first line (1L) therapy were included in this analysis. Clinical characteristics and 1L and 2L therapies were abstracted from MER and by chart review; treatment outcomes were analyzed. Results: Among a total of 343 MCL patients with a median follow-up of 11.8 years, 188 had documented progression/relapse to 1L therapy, of which 170 had 2L treatment information available for this analysis. At the time of 2L therapy, 123 (72%) patients had an age >60, 136 (80%) were male, 132 (78%) had stage III/IV, and simplified MIPI was 0-3 (low) in 37 (35%), 4-5 (intermediate) in 40 (37%), and 6-11 (high) in 30 (28%; simplified MIPI missing in 63 patients). The median time from diagnosis to 2L was 27 months (range 0.5-141). The patterns of 1L and 2L treatment are shown in Figure 1. 1L treatment included HiDAC-based (n=31, 13 had autologous stem cell transplant [ASCT]), R-CHOP-like (n=79, 45 had ASCT), R-Bendamustine (BR, n=22, 2 had ASCT), other systemic (n=29), and non-systemic (n=9). 15 patients (9%) received rituximab maintenance after induction or ASCT. 2L treatment included salvage therapy followed by ASCT (n=13; salvage with HiDAC-based n=2, R-CHOP-like n=5, BR n=3, platinum-based n=2, other n=1) or Allogeneic SCT (AlloSCT, n=5), HiDAC-based n=9, R-CHOP-like n=6, BR n=33, BTK inhibitor (BTKi, n=21), other targeted therapy (lenalidomide, bortezomib, mTOR inhibitors, n=26), other systemic (n=47), and non-systemic (n=10). The median follow-up from 2L therapy was 8.2 years. The objective response rate to 2L therapy was 71% (45% complete response). The median progression-free survival (PFS) and overall survival (OS) were 1.1 and 4.0 years, respectively. The 2-year PFS rate and 5-year OS rate were 55% (95% CI 36-84) and 71% (95% CI 49-100), respectively for patients treated with BTKi at 2L, and 42% (95% CI 28-63) and 46% (95% CI 32-68), respectively, for those treated with BR. In patients intended to undergo salvage therapy followed by ASCT (n=18, n=13 transplanted) or AlloSCT (n=5, all transplanted), the 2-year PFS rate and 5-year OS rate were 80% (95% CI 52-100) and 60% (95% CI 41-88), and 80% (95% CI 52-100) and 61% (95% CI 42-88), respectively. Patients treated with HiDAC-based, R-CHOP-like, other targeted therapy, or other systemic therapy had poorer outcomes (2-year PFS 0-27%, 5-year OS 0-35%). Image:Summary/Conclusion: Second line treatment for MCL was very heterogenous in terms of treatment and outcomes and was likely impacted by 1L treatment and other clinical factors. The evolution of 1L and R/R MCL treatment patterns and the associated patient characteristics and outcomes requires further exploration in larger datasets, given extensive heterogeneity in practice patterns.